package com.liu.tools;

import java.io.IOException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

import com.liu.tools.base64.Base64;

/**
 * @DateTime 2015年7月14日 下午7:01:47
 * @Company 华视传媒
 * @Author 刘兴密
 * @QQ 63972012
 * @Desc DES加密和解密
 */
public class DESUtil {

	    private final static String DES = "DES";
	   
	    /**
	     * Description 根据键值进行加密
	     * @param data 
	     * @param key  加密键byte数组
	     * @return
	     * @throws Exception
	     */
	    public static String encrypt(String data, String key) throws Exception {
	        byte[] bt = encrypt(data.getBytes(), key.getBytes());
	        String strs = Base64.encodeToString(bt, Base64.DEFAULT);
	        return strs;
	    }
	 
	    /**
	     * Description 根据键值进行解密
	     * @param data
	     * @param key  加密键byte数组
	     * @return
	     * @throws IOException
	     * @throws Exception
	     */
	    public static String decrypt(String data, String key) throws IOException,
	            Exception {
	        if (data == null)
	            return null;
	        
	        byte[] buf = Base64.decode(data, Base64.DEFAULT); //decoder.decodeBuffer(data);
	        byte[] bt = decrypt(buf,key.getBytes());
	        return new String(bt);
	    }
	 
	    /**
	     * Description 根据键值进行加密
	     * @param data
	     * @param key  加密键byte数组
	     * @return
	     * @throws Exception
	     */
	    private static byte[] encrypt(byte[] data, byte[] key) throws Exception {
	        // 生成一个可信任的随机数源
	        SecureRandom sr = new SecureRandom();
	 
	        // 从原始密钥数据创建DESKeySpec对象
	        DESKeySpec dks = new DESKeySpec(key);
	 
	        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
	        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
	        SecretKey securekey = keyFactory.generateSecret(dks);
	 
	        // Cipher对象实际完成加密操作
	        Cipher cipher = Cipher.getInstance(DES);
	 
	        // 用密钥初始化Cipher对象
	        cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
	 
	        return cipher.doFinal(data);
	    }
	     
	     
	    /**
	     * Description 根据键值进行解密
	     * @param data
	     * @param key  加密键byte数组
	     * @return
	     * @throws Exception
	     */
	    private static byte[] decrypt(byte[] data, byte[] key) throws Exception {
	        // 生成一个可信任的随机数源
	        SecureRandom sr = new SecureRandom();
	 
	        // 从原始密钥数据创建DESKeySpec对象
	        DESKeySpec dks = new DESKeySpec(key);
	 
	        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
	        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
	        SecretKey securekey = keyFactory.generateSecret(dks);
	 
	        // Cipher对象实际完成解密操作
	        Cipher cipher = Cipher.getInstance(DES);
	 
	        // 用密钥初始化Cipher对象
	        cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
	 
	        return cipher.doFinal(data);
	    }
	
}
